JPS62279170A - Steering force control device for power steering device - Google Patents

Abstract

PURPOSE:To smooth return control of a handle through prevention of production of an assist force, by providing a return detecting means which detects that a steering angle is changed in a direction in which it approaches a neutral position. CONSTITUTION:An electromagnetic throttle valve 90 is connected to a passage 45 on the reaction force side, and is communicated to a tank through throttle of the valve 90. The valve 90 is connected to a computer 91 for controlling a steering force through a driving circuit 90a, and the opening thereof is controlled according to an instruction from the computer 91. Singals from a steering angle detector 92 for detecting the steering angle of a handle H and a car speed detector 93 are inputed to the computer 91. A current responding to a car speed V and a steering angle theta is fed to the valve 90, and a reaction force chamber 56 is controlled to a value responding to the car speed V and the steering angle theta, and an optimum steering reaction force is exerted. In a handle neutral position, a steering reaction force is decreased, and catching phenomenon during steering of a handle can be prevented from occurring.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention provides a reaction force mechanism that supplies reaction oil pressure according to vehicle speed, etc., and changes steering torque according to vehicle speed, etc. The present invention relates to a steering force control device for a power steering device equipped with a power steering device.

<Prior Art> It is known that a reaction force hydraulic pressure proportional to vehicle speed or the like is introduced into a reaction force mechanism to control the steering force of a power steering device in accordance with vehicle speed or the like.

<Problems to be Solved by the Invention> However, according to such a steering force control device, although the characteristics related to the steering feel can be improved by 1, there is a problem in that the poor return of the steering wheel cannot be improved.

Means for Solving the Problems> The present invention provides a steering angle detector that detects a steering angle, and a steering angle that detects a steering angle that is changing in a direction approaching a neutral position. The present invention is characterized by providing a return detection means for detecting the return detection means, and a control means for increasing the pressure of the pressure oil supplied to the reaction force mechanism in response to the output of the return detection means.

<Function> When the handle is steered deeply from the cut state to the return direction,
This is detected by the return detection means, and the pressure of the pressure oil supplied to the reaction force mechanism is increased by the action of the control means.

As a result, the servo valve is maintained in a state close to a neutral state, generation of assist force is prevented, and the return operation of the handle is performed smoothly.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1 (al), 11 is a housing main body forming the main body of the power steering device, and 12 is a valve housing fixed to the housing main body 11.
A pinion shaft (output shaft) 21 is rotatably supported within the valve housing 12 via a pair of bearings 13 and 14, and a rank shaft that is slidable in a direction intersecting the pinion shaft 21 is rotatably supported within the valve housing 12. 22 rack teeth 22a are in mesh with each other. This rack shaft 22 is connected to a piston of a power cylinder (not shown), and both ends thereof are connected to steering wheels via a required steering link mechanism.

A control valve mechanism 30 is housed within the hole of the valve housing 12. The control valve mechanism (servo valve) 30 includes a rotary valve member 31 integrally formed with an input shaft 23 as a steering shaft.
The main component is a sleeve valve member 32 that is fitted around the outer periphery of the rotary valve member 31 so as to be concentric and relatively rotatable.

The rotary valve member 31 is connected to the pinion shaft 21 via a torsion bar 24 whose one end is connected to an input shaft 23 integral with the rotary valve member 31.
flexibly connected to. In addition, the rotary valve member 31
Although not shown, a plurality of lands and grooves extending in the axial direction are formed at equal intervals on the outer periphery of the holder, and a communication path 37 is bored through the bottom of the groove to communicate with the inner periphery. There is. The input shaft 23 is provided with a passage 39 that communicates the inner peripheral portion with the low pressure chamber 38 within the valve housing 12 .

On the other hand, a plurality of lands and grooves extending in the axial direction are formed at equal intervals on the inner circumference of the sleeve valve member 32, and distribution holes 40.
41 are provided. When the control valve is in the neutral state, the pressure fluid supplied from the supply port 35 flows equally into the grooves on both sides of the land portion, and flows out from the low pressure chamber 38 to the discharge port 36 via the communication passage 37 and the passage 39. In this case, both distribution ports 33, 34 are at low and equal pressure, so the power cylinder is not activated. If the control valve deviates from the neutral state, pressure oil is supplied from the supply port 35 to one distribution hole 40 or 41, and pressurized oil is supplied from the supply port 35 to the other distribution hole 41 or 40.
Fluid discharged from the power cylinder flows into the chamber and is discharged to the discharge port 36 through the communication passage 37, passage 39, and low pressure chamber 38.

The reaction force mechanism is as follows. At the end of the rotary valve member 31 on the pinion shaft 21 side, as shown in FIG. The pinion shaft 21 is formed with a fitting groove 51 into which the protrusion 50 is loosely fitted so as to be rotatable by several angles around the axis of the input shaft 23. At the tip of the protrusion 50, an engagement groove 52 having a letter-shaped cross section is formed in the axial direction. The insertion hole 53 has a distal end that is connected to the engagement groove 5.
2 is slidably inserted in the radial direction, and an annular groove 55 is formed to guide hydraulic oil to the rear part of the plunger 54.
5 constitutes a reaction force chamber 56. Reference numeral 58 is a boat that introduces pressure fluid from a pump controlled according to the vehicle speed, etc., and 57 is a passage that communicates the boat 58 with the annular groove 55.

The reaction force mechanism configured as described above is a so-called radial type, but may also be a thrust type configured to apply a reaction force in the axial direction.

Reference numeral 60 indicates a supply pump driven by an automobile engine, and reference numeral 61 indicates a flow rate control valve that controls the pressure oil discharged from the supply pump 60 to a constant flow rate Q. The flow rate control valve 61 is operated according to the metering orifice 62 and the longitudinal pressure of the metering orifice 62, and controls the opening of the bypass passage 63 leading to the low pressure side so as to keep the longitudinal pressure constant. It is constituted by a bypass valve 64. It should be noted that if the supply pump 60 is a constant speed motor-driven type that discharges a constant flow rate, the flow rate control valve 61 is not necessary.

Reference numeral 80 denotes a flow divider that is connected to the high pressure side of the flow control valve 61. This branch control valve 80 is
The flow rate Q is caused by sliding the control spool 81 using the differential pressure across the control throttle 70a and a spring, and diverts the flow rate QG to the servo valve side passage 44, and also to the reaction force mechanism side passage 45.
The flow rate QR is diverted to.

An electromagnetic throttle valve 90 is connected to the reaction force mechanism side passage 45, and communicates with the tank via the throttle of the electromagnetic throttle valve 90. This electromagnetic throttle valve 90 is of a type in which the opening degree decreases as the supplied current increases, and is connected to a computer 91 for steering force control via a drive circuit 90a, and the opening degree is controlled by instructions from the computer 91. It is now possible to do so.

Signals from a steering angle detector 92 for detecting the steering angle of the steering wheel H and a vehicle speed detector 93 are input to the computer 91. The steering angle detection unit 392 includes a slit-type rotational displacement detector 92a and an addition/subtraction counter 92b that counts pulses from the rotational displacement detector 92a to detect the absolute steering angle of the steering wheel H. .

FIGS. 2(a) and 2(b) are flowcharts showing the processing of the computer 91, and the computer 91 executes these programs at regular intervals.

FIG. 2(a) shows a process for determining the steering direction. First, in step 100, the steering angle θ is read from the addition/subtraction counter 92b, and a positive/negative determination is made, that is, it is determined whether the steering shaft is rotating clockwise or counterclockwise. In case of clockwise rotation, step 102
The deviation from the previous input value 0θ is calculated. If it is determined to be negative, the process moves to step 104. In step 104, it is determined that the vehicle is being steered in a direction in which the absolute value of the steering angle increases, so the parameter NEGA is set to 0 to store this fact. Further, if it is positive, that is, if the steering angle is being steered in a direction in which the absolute value of the steering angle is decreasing, NEGA is set to 1. If the steering direction is to the left, a similar determination is made in step 108, and if the steering is being carried out in a direction in which the absolute value of the steering angle increases, N is determined in step 112.
EGA is set to 0, and if the vehicle is being steered in a direction in which the absolute value of the steering angle is decreasing, NEGA is set to 1 in step 110. In step 114, the steering angular velocity θ is determined using the data of the processing interval T. In step 116, the currently input steering angle θ is stored as Oθ.

Next, the reaction force control process shown in FIG. 2(b) will be explained.

In step 200, the vehicle speed ■ is input from the vehicle speed detector 93, and in step 202, the steering angle θ is input from the addition/subtraction counter 92b. After this, in step 204, the control current value 1. is determined according to the vehicle speed ■ and the steering angle θ. Read out from the national map.

After this, in step 206, FIG.
The result determined by the process is determined, and if the steering is being performed in the direction in which the absolute value of the steering angle increases (cutting), the process moves to step 208, and the return control current value r is determined.
After setting R to zero, the process moves to step 210 and Io
The output current value Tau is calculated by calculating ut=Io+11+1.
t is determined and outputted to the drive circuit in step 212.

As a result, the electromagnetic throttle valve 90 is supplied with a current according to the vehicle speed ■ and the steering angle θ, and the pressure in the reaction force chamber 56 is controlled to a value according to the vehicle speed V and the steering angle θ, so that the optimum steering reaction force is obtained. will be granted.

On the other hand, if it is determined that the steering wheel I (is being steered in the return direction), the process moves from step 206 to step 214, and with reference to the map shown in FIG. Derive the return control current value IR,
Based on this, the output current value Iout is calculated.

The map shown in FIG. 3 shows that IR is zero when the absolute value 1θ1 of the steering angle is near zero, and when lθ] becomes greater than or equal to the set angle 1θS1, IR is zero? has a characteristic that increases up to the set value Is. Therefore, when the angle of the handle I (is turned from the neutral position by more than the set angle), the output current Tout becomes a value larger than the current at the time of cutting by Is, and a larger reaction force is generated than at the time of cutting. The servo valve is held close to the neutral position, making it difficult to generate steering assist force and improving the return of the steering wheel.Also, at the neutral position of the steering wheel, 1θ1 is zero and IF? is also zero, so
The steering reaction force is reduced, and it is possible to prevent the steering wheel from getting stuck when steering.

Note that instead of the map shown in FIG. 3, a map that defines the return control current IR with respect to the absolute value [il of the steering angular velocity is stored as shown in FIG. 4, and this map is referred to in step 214 to determine the return control current. IR may also be obtained.

<Effects of the Invention> As described above, in the present invention, it is detected that the steering wheel is steered in the return direction, and the reaction oil pressure is increased, thereby returning the servo valve to the neutral state.
This has the advantage of improving the return characteristics of the handle.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a power steering device showing an embodiment of the present invention with a hydraulic system diagram, FIG. 2 is a flowchart showing the operation of the computer 91 in FIG. 1, and FIG.
FIG. 4 is a diagram showing a map for determining R. FIG. 4 is a diagram showing a modified example of the map. 21... Binion shaft, 23... Input shaft, 56...
Reaction force chamber, 80... Diversion control valve, 90... Electromagnetic throttle valve, 91... Computer, 92... Steering angle detector,
93...Vehicle speed detector.

Claims (1)

[Claims] (1) A servo valve that is operated based on the relative rotation between the input shaft and the output shaft and controls the supply and discharge of pressure oil to the power cylinder;
A steering angle detector that detects a steering angle in a steering force control device for a power steering device that is equipped with a reaction force mechanism that applies a force to return a servo valve to the neutral side depending on the supply of pressure oil to change steering wheel torque. a return detection means for detecting that the steering angle detected by the steering angle detector is changing in a direction approaching the neutral position; and a return detection means for supplying the output of the return detection means to the reaction force mechanism in response to the output of the return detection means. 1. A steering force control device for a power steering device, comprising a control means for increasing the pressure of pressure oil.